def solve(x):
    if x >= 30:
        return "Yes"
    else:
        return "No"


def main():
    x = int(input())
    res = solve(x)
    print(res)


def test():
    assert solve(25) == "No"
    assert solve(30) == "Yes"


if __name__ == "__main__":
    test()
    main() def solve(x):
    if x >= 30:
        return "Yes"
    else:
        return "No" solve if x >= 30:
        return "Yes"
    else:
        return "No" x >= 30 x 30 return "Yes" "Yes" return "No" "No" x x def main():
    x = int(input())
    res = solve(x)
    print(res) main x = int(input()) x int(input()) int input() input res = solve(x) res solve(x) solve x print(res) print res def test():
    assert solve(25) == "No"
    assert solve(30) == "Yes" test assert solve(25) == "No" solve(25) == "No" solve(25) solve 25 "No" assert solve(30) == "Yes" solve(30) == "Yes" solve(30) solve 30 "Yes" if __name__ == "__main__":
    test()
    main() __name__ == "__main__" __name__ "__main__" test() test main() main def solve(x):
    if x >= 30:
        return "Yes"
    else:
        return "No" def solve(x):
    if x >= 30:
        return "Yes"
    else:
        return "No" solve def test():
    assert solve(25) == "No"
    assert solve(30) == "Yes" def test():
    assert solve(25) == "No"
    assert solve(30) == "Yes" test def main():
    x = int(input())
    res = solve(x)
    print(res) def main():
    x = int(input())
    res = solve(x)
    print(res) main
def solve(x):
    if x >= 30:
        return "Yes"
    else:
        return "No"


def main():
    x = int(input())
    res = solve(x)
    print(res)


def test():
    assert solve(25) == "No"
    assert solve(30) == "Yes"


if __name__ == "__main__":
    test()
    main()
